In a tomography system, a detector, which usually comprises an array of detector elements, provides signals in response to radiation received along different radiation paths through a subject, and these signals are processed to reconstruct a tomographic image of the subject. In the design of systems for the acquisition of data from the radiation detector, it is assumed that the information content for each radiation path through a subject is the same. It has been found that the information content is not the same for all radiation paths and that the information content is less for paths outward of a central path through the center of a subject. The present invention makes use of such recognition to provide a tomography data acquisition system in which the data channels are implemented in accordance with the respective information content for the associated radiation paths, with resultant reduction in the cost and quantity of signal processing apparatus needed for outward radiation paths.